Plunger-type lock



Oct. 3, 1961 s. M. MOBERG PLUNGER-TYPE Loox Filed Aug. 5, 1960 IN VENTOR: 5/60@ M. MME/e@ 3,0()2,368 PLUNGER-TYPE LOCK Sigurd M. Moberg,Pompton Plains, NJ., assgnor to E. J. rooks Company, Newark, NJ., acorporation of New ersey Filed Aug. 3, 1960, Ser. No. 47,269 6 Claims.(Cl. 70-14) 'Ihis invention relates to improvements in plungertype locksof the general character disclosed in my previously led applicationSerial No. 33,271 (series of 1960), filed June l, 1960. Moreparticularly, this invention relates to improvements in the lock whichhave the eiect of rendering the lock much more diicult, indeed, wellnigh impossible to pick or open without a proper key.

The stated object of rendering the lock more difcult or impossible topick is achieved by the present invention of which a preferredembodimetn is shown Vin the accornpanying drawing without, however,limiting the invention to that particular embodiment.

In the drawing: A

FIGURE 1 shows the improved lock as applied to y'a iixed arm and amovable valve arm to hold those arms in registering relationship for thepurpose of locking a valve in a pipeline in closed position.

FIG. 2 shows the lock in with a valve in a pipeline but top of the lock.

FIG. 3 is an enlarged central axial sectional View of the locksubstantially on the line 3-3 of FIG. 1; the lock being shown in lockedcondition.

FlG. 4 is a view substantially similar to FIG. 3 but showing the effectof an attempt to open the lock by means other than a key particularlydesigned and provided for that purpose.

The lock, identiiied generally by the reference character 12, comprisesa generally cylindrical shank 14, an enlarged head 16 ixedly integralwith said shank at one end of the latter (the upper end as illustratedin the drawing), and a removable, cup-shaped head or cap 18 which isadapted to be locked to and released from the lower end of the shank 14by means hereinafter described.

In the use illustrated in the drawing, a valve 20 in a pipeline 22 isprovided with a iixed or stationary arm 24 and a movable valve-operatingarm 26. If it is desired that the valve 2t) be locked in closedcondition, the arm 26 is brought to its position as indicated in fulllines in FIGS. 1 and 2 in which an aperture 28 therein registers with asimilar aperture 30 in the stationary arm 24. Then the lock, minus itsremovable cap 18, is applied to the mentioned valve arms by introducingthe shank 14 downwardly through the apertures 28 and 30 until theenlarged head 16, which is larger than the aperture 28, abuts againstthe portions of the arm 26 which dene said aperture. That leaves theshank 14 extending through the apertures 28 and 30 and substantiallybelow the arm 24. Then, by suitable use of a key, the cap 18 is appliedand locked upon the lower end of the shank. It should be obvious that,by similar use and manipulation of the lock and its various parts, itmay be employed with various kinds of members to lock them together. Thepresent invention, however, is concerned more directly with improvedmeans embodied in the lock making it more diicult, and, indeed, wellnigh impossible, yfor the cap 18 to be removed from the shank 14 exceptby the use of a proper key.

Referring particularly to the cap 18 is provided with two internalannular grooves 32 and 34 within one or the other of which a pair ofsteel balls 36 seats and is held seated by a plunger 58 which extendswithin a counterbore 40 in the lower end of the shank 14 and thejust-stated association looking down upon the FlG. 3, it may be seenthat aired States Patenti@ at least one and possibly with lice blocksthe balls 36 trom moving radially inwardly in transverse bores 42 withinwhich they are disposed. As the balls are thus held against shitting inthe bores 42 in the shank of the lock, it follows that the balls areheld securely in place extending partly within one or the other of theannular grooves 32 or 34 so that the cap 18 is held securely againstremoval from the remainder of the lock. The lower end of the plunger 38is formed with a reduced portion 44 and, when the plunger is shiftedupwardlyr by suitable key means to the point where portion 44 is inalignment with the balls 36, the latter are free to move radiallyinwardly within the shank to `a sufficient extent to allow them to beentirely clear of the cap 18 whereupon the latter may easily be removedto open the lock.

The plunger 38 is formed with an integral annular shoulder 46, which, byabutment with an annular ledge 48 in the shank 14, limits the downwardmovement of the plunger 38 to its locking position as indicated in FIG.3. The plunger is normally held yieldably downwardly in such lockingposition by a coil spring 56 which encircles an upper extension 52 ofthe plunger 38, both of which are disposed within a main bore 54 in saidshank. The spring 50 is compressed between the upper surface of theshoulder 46 and an undersurface 56 oi a plug 58 which is forcetted,screw-itted, or otherwise firmly fitted into an enlarged bore 60 in thehead 16.

It will be observed that the plug 58 is formed with a main bore 62 atits lower end and a counterbore 64 at its upper end. The main bore 62 isonly slightly larger than the outside diameter of the upper end of theextension 52 of the plunger so that, it means for unlocking the lock aresuch as to maintain the extension 52 in axial alignment with the bore 62of the plug, the plunger 38 may, by suitable key means, be raisedagainst the compressive force of the spring 50 to an extent sufiicientto bring the reduced portion 44 of the plunger into alignment with theballs 36 so that the latter may move inwardly and release the cap 18 forremoval.

The upper end of the plungers extension 52. is formed with a bore 66ofthe same internal diameter as the counterbore 64 of the plug and inaxial alignment with said counterbore.

A key for opening the lock preferably includes a pair of elongate ngers68 and 70, each of which is substantially semi-circular in cross sectionand of such dimensions that, when the two mentioned ngers are innon-locking relationship as hereinafter explained, they may be inserteddownwardly into and through the counterbore 64 and also into the bore66. As the bores 64 and 66 are of the same internal diameter andas thekey fingers 68 and 70 slide freely within and into said bores but with afairly accurate lit, it follows that when said key iingers are in use tooperate the lock, they hold the plunger 38 and, more particularly, itsupper extension 52 in perfect alignment with the bore 62 in the plug 58.Because of such alignment, the plunger of the lock may be raised by saidkey fingers without any interference against entry of the plungersextension 52'into the bore 62, and movement of the reduced lower endportion 44 of the plunger into alignment with the balls 36 permits thelatter to move inwardly and, thus, release the .cap 18 for removal.

As the key for operating the lock forms no essential part of thisinvention, only the ngers 68 and 70 of a key are illustrated. The keyincludes means (not shown herein but shown in my mentioned earlierapplication) for .enabling the user to move the fingers 68 and l70longitudithe upper extension 52 in 62. Therefore,

tively to the finger 68, a cam portion 72 at the lower end of yfinger 70rides upwardly upon a cam surface 74 at the lower end of linger '68 sothat the two fingers of the key are forcibly urged away from each otherat their lower ends. This causesr the lower ends of the fingers,previously quite free of material frictional engagement or grippingcontact with the surface of the bore 66 as upon original insertion ofthe key, to enter into very tight frictional engagement with the wallsof said bore. When, after such gripping contact, the key is bodilypulled upwardly, the key ngers 68 land 70 pull the plunger 38 upwardlyto permit the balls 36 to be freed from locking engagement with the cap18 to enable the latter to -be removed in the manner already explained.By similar operation of the key, the cap 18 may be replaced upon theVlock after which the key may be manipulated to cause the linger 70 toslide downwardly inrelation to finger 68 and thereby release-the tightfrictional engagement of said lingers with the wall defining the bore66. Then, the key may be removed from the lock and the spring 50 willhold the plunger in locked condition in the manner already explained.

The arrangement -by means of which such a lock, according to thisinvention, is rendered substantially lpickproof resides chiefly incertain characteristics, relative sizes and relationships of variousparts of -the lock with reference to each other and also in certaindispositions of those parts as will now be explained. It will beobserved that the diameters of the locking portion of the plunger 38 andof the bore 40 are substantially dierent and, likewise, that the outsidediameter of the annular shoulder 46 and the inside diameterof the mainbore 54 are quite different.

The mentioned differences are such that the plunger 38 and its shoulder46 are not merely a sloppy t within the bores 40' and 54 but aresuliiciently smaller than the mentioned bores that the plunger iscapable of substantial tilting relatively to other parts of the lockunless, by proper key means, such as the described fingers 68 and 70,the upper end of the plunger is positively held in coaxial relationshipto the remainder of the lock. Such possible tilting is furtherfacilitated by reason of the fact that the spring 50 is slightly conicalin shape with its larger, upper end disposed considerably outwardly ofthe bore 62 and the outer surface of -the upper extension 52 of theplunger. Moreover, the spring 50 may advantageously be so formed thatits bottom end bears non- -uniforrnly upon the shoulder 46 so that whilethe-seating of the conical undersurface of said shoulder, in lockingposition, serves to hold the plunger in non-tilted position to receive akey thereinto, the non-uniform spring action will tend to tilt theplunger immediately upon -unseating of said shoulder, unless, of course,a proper key-has been used, holding the plunger against tilting.

The practical pick-proofing elect of rendering the plunger easilytiltable, as just explained, may best be understood by reference toAFIG'. 4. In-considering that tigure, it may be assumed that aninterloper, attempting to open the lock without having a proper key,would resort to something in the nature of a bent piece of wire such asis shown at 76. Before attempting to use the wire, the interloper,perhaps having some knowledge or theory las to how the lock operates,would lirst bend or form a hook 78 at its lower end. He would theninsert the hooked end of the wire into the lock and into the bore 66. Inattempting to cause the hook 78 to jam against the wall of the bore 66,he almost certainly would cant or tilt the wire tosome extent, and indoing so, would tilt the plunger 38, throwing the upper extension'SZofthe plunger toward one'side or,fi.e., out of ycoaxial alignment withthe bore 62 in the plug.

Even if the wire werenot thus canted, itis almost certain'that the wirecould not serve as a means for holding perfect alignment with-the boreafter the hook 78 is jammed within-the bore 66, any upward pull of thewire 76, intended to open the lock would serve only to lift the plungerto a point where the upper end of the extension 52 would abut againstthe undersurface 56 of the plug 58 as shown in FIG. 4. In thatcondition, the-plunger 38 would still be in restricting position withreference to the steel balls 36 so that the latter would still seatwithin the groove 34 (or the groove 32) to prevent removal of the cap18. Thus, it will be seen that where a plunger lock is given thecharacteristics of the present invention it is renderedpracticallyunopenable except Vwith a proper key.

Obviously, the shapes, relative sizes, and inter-relationships of thevarious parts of the lock may be varied considerably while,nevertheless, employing the principles of the present invention.

I claim:

1. A plunger-type lock comprising a body, a tiltable plungerreciprocable endwisely in said body between locking and unlockingpositions, a portion of said body having an inner abutment surface inposition to interfere with said plunger to prevent endwise movement ofthe latter to its said unlocking position when the plunger is tilted,said body being formed with a recess, coaxial with said plunger andadapted to receive a portion of the plunger when the latter isnon-tilted to permit endwise movement of said plungerto its saidunlocking position, said plunger being formed with an axial bore,opening toward said recess, and said recess opening at the exterior ofthe lock and ybeing adapted to receive a key adapted to engage saidplunger within said bore to hold the plunger in non-tilted condition andmove the plunger from its locking to its unlocking position.

2. A plunger-type lock comprising a cylindrical body, an enlarged headintegral with one end of said body, a cap slidable onto the other end ofsaid body, releasable locking means carried by said body at its saidother end and adapted, except when released, to interengage between andinterlock said body and said cap, a tiltable plunger disposedsubstantially coaxially in said body, reciprocable between a lockingposition, in which a portion of said plunger, toward one end thereof,coacts with said locking means to hold the latterin such interlockinginterengagement between said cap and body and a non-locking positionwherein said plunger is free of such holding coaction with said lockingmeans, said enlarged head being formed with an internal recess coaxialwith said plunger and adapted, in the absence of tilting of the plunger,`to receive the other end of the latter in an accurate sliding dit topermit movement of the plunger to non-locking position, said plunger,when tilted, being incapable of having its said other end move into saidrecess and thus incapable of moving to non-locking position, and saidlock being formed with a coaxial aperture at one of its ends, adapted toreceive a key which is adapted to engage said plunger to hold the latterin non-tilted condition and move it to unlocking position.

3. A plunger-type lock comprising a cylindrical body formed with anenlarged portion on one end thereof, a coaxial main bore, a coaxialcounterbore adjoining said main bore at an inner ledge of said body, anda transverse bore lextending from said counterbore to the exterior ofsaid body, a cap slidable onto the other end of said body and formedwith an internal annular groove, a locking element in said transversebore engageable within said groove to retain said cap upon said body andmovable inwardly in said transverse bore to disengage said groove topermit removal of said cap, a tiltable, axially reciprocable plungerhaving an annular shoulder, engageable with said ledge to limit movementof said plunger in one direction, a cylindrical locking portionextending within lsaid counterbore adapted, when in transverse alignmentwith said locking element, to hold the latter in engagement within saidgroove, a cylindrical key-receptive portion extending within vsaid mainbore, yieldable means within said body urging said plunger toward alocking position in which said shoulder abuts said ledge, saidkey-receptive portion of the plunger having a coaxial bore and beingadapted to fit with an accurate sliding tit within an opposed recess insaid body, and said body having a keyhole, coaxial with said bore in thekey-receptive portion of the plunger and of substantially similardiameter as the last-mentioned bore, and an annular abutment surfacedefining the inner end of said keyhole and adapted, when said plunger istilted, to interfere with said plunger to prevent movement of the lattertoward an unlocking position in which said locking portion is free ofsaid holding engagement with said locking element; said keyhole and saidbore in the plunger being adapted to cooperate with a key memberextending through the keyhole Vand into the latter bore to hold saidplunger against material tilting to enable the plunger to be moved bysaid key member to said unlocking position.

4. A lock according to claim 3, said locking element being a rigid ball.

5. A lock according to claim 3, said main bore and counterbore being ofsubstantially greater diameters, respeotively, than said key-receptiveand locking portions of the plunger, rendering the latter substantiallytiltable except when held against tilting by such a key member.

6. A lock according yto claim 3, said yieldable means comprising a coilspring extending within said main bore and about said key-receptiveportion of the plunger and compressed between said ledge and saidannular abutment surface, and the outside diameter of said keyreceptiveportion, adjacent to the latters free extremity, being substantiallyless than the inside diameter of said spring to avoid materialinhibition, by said spring, of tilting of said plunger.

References Cited in the tile of this patent UNITED STATES PATENTS

